Soil pH is determined by the four main cations; Calcium, Magnesium, Potassium and Sodium.
Each of these elements effects pH to a different degree with the 39% Magnesium in Golden Bay Dolomite lifting the pH 1.66 x more than straight Calcium found in normal ag lime.
So for every one ton of dolomite applied you lift the pH higher than the equivalent one ton of lime.
Address the main cation levels and pH will take care of itself.
A critically important element Calcium should be viewed for its effect on plant and animal nutrition along with microbial health more than adjusting pH alone.
Known as the ‘King of nutrients’ calcium is the trucker of all minerals because it is intimately involved in the movement of nutrients in and out of the cell. Calcium is also the key mineral determining cell strength as, in combination with Silica; it is built into the cell wall. Shelf life, resistance to disease and reduced insect pressure are all benefits if increased cell strength.
Dolomite is a major source of calcium, a deficiency of which causes stunted growth, restricted leaf development and paleness at leaf margins.
Adjusting the Calcium / Magnesium levels in the soil with a calculated application of Dolomite, will reduce soil acidity (lift pH) and therefore ensure better over all nutrient availability.
The presents of broadleaf weeds are an indicator that Calcium is lacking. This alone should be enough to indicate the need for Dolomite or Lime, but look for other signs. Checking the “brix” levels (sugar content) in pasture with a refractometer offers a reliable guideline to calcium levels.
If the plant contains adequate levels of calcium, the indicator line is fuzzy and indistinct, but it sharpens and becomes more defined as calcium becomes deficient. If the sap pH is low in pasture this also helps to confirm a calcium shortage.
It is obvious that if you are exporting calcium off the farm twice a day as milk (dairy farming), you need to compensate for this removal. If a penetrometer reveals a tight, closed soil with a hard pan at 20cm, this is yet another indicator of a soil screaming out for the flocculating force of calcium.